Generally, a valve assembly formed by sequentially connecting a plurality of manifold valves has been used for controlling the pneumatic device such as an air cylinder. The valve assembly is normally disposed around the pneumatic device such that the respective manifold valves are connected to the pneumatic device via air pipes, and further electrically coupled with a serial unit via a lead wire. The respective manifold valves may be driven by electric signals from the serial unit.
Japanese Unexamined Patent Application Publication No. 2002-51385 discloses a control system using the aforementioned valve assembly, which is structured to control solenoid valves (manifold valves) of the solenoid valve manifold (valve assembly) using serial signals. The control system is formed of the solenoid valve manifold structured by mounting a plurality of solenoid valves on the manifold, and a serial transmission mobile unit (serial unit) for serial transmission to the sequencer. The solenoid valve is driven upon reception of power from the serial transmission mobile unit based on the serial signal from the sequencer.
In the generally employed control system as described above, the solenoid valve manifold and the serial transmission mobile unit correspond one by one. When the serial transmission mobile unit outputs 32 points, 16 solenoid valves each of double solenoid type are assembled. The aforementioned solenoid valves are connected to the corresponding air cylinders via the respective air pipes. However, all the air cylinders are not provided around the solenoid valve manifold. In most of the case, some of the air cylinders are disposed apart from the solenoid valve manifold. In such a case, the long air pipe is required for connecting the air cylinder apart from the solenoid valve manifold, thus causing problems of increase in the air consumption and the response delay.
The solenoid valve manifold may be divided into a plurality of sections so as to be disposed around the air cylinder for solving the aforementioned problem. In this case, the serial transmission mobile unit is also required to be divided into plural sections, or the single serial transmission mobile unit is required to extend different numbers of lead wires with different lengths to the plural sets of the solenoid valve manifolds with the different numbers of the solenoid valves and at the different positions, resulting in complicated system structure.